The present invention relates to a system for transmitting power and converting torque mechanically so as to provide positive linkage between a power input shaft and a powered output shaft in ratios that can be infinitely varied, i.e. infinitely variable ratio or IV. The construction is a hybrid solution to the problem of enabling a gearbox to operate as a hydraulic torque converter, i.e. provide any input-to-output speed ratio between two limit values. The hydraulic analogy stems from the fact that the equivalent of a pump is provided and that the "fluid flow" of that pump drives the equivalent of a hydraulic motor. The "fluid" is replaced herein by mechanical links (balls) which can transmit pressure (push), but cannot exert suction (pull). Those mechanical links provide the positive mechanical connection between the shafts which eliminates the possibility of slippage and provides the additional possibility of positive locking.
In a prior Inventor's patent (U.S. Pat. No. 4,739,669), balls positioned between two cylindrical surfaces of two shafts enable them to be mechanically connected. These balls, when properly guided and restrained, facilitate the transformation of sliding motion into rotating motion (and vice versa) by means of cooperating grooves on two parallel surfaces. In the cited reference, one groove is straight (axially-oriented) and another is helically laid. Two sets of such conjugate grooves and their associated balls, connected as the links of a chain, provide the equivalent of a push rod that can follow and conform to a variety of contoured shapes with a minimum of friction. The state-of-the-art of such technology is old and extensively used in many well-known applications in mechanical engineering.
The use of cylindrical shaft surfaces to locate the helically-laid grooves allows to minimize the drive outer diameter but at the expense of the drive length. For some applications, such as bicycles, it is advantageous to minimize length at the expense of outer diameter. In one embodiment of the present invention, maximum transmission shortening is achieved with the use of spirally-laid grooves located on planar surfaces such as those of two conjugate flanges mounted one on each shaft. The straight grooves are then oriented in a radial direction. For automotive applications such as cars, buses and trucks, shortening of the transmission to an extreme may not be as advantageous and the use of helically-laid grooves on concentric conical surfaces might prove more beneficial. The straight grooves are then oriented along the conical surface generatrices. Spiral grooves on a planar surfaces correspond to the planar projections of helical grooves on conical surfaces. In both instances, the continuous ball-linked chain of the referenced invention must be split into a plurality of independent and unconnected closed ball-linked chains.
It seems that a generalized usage of such constuction as optimized for each application may be of considerable advantage. The combination of advantages resulting from the use of an efficient IV torque converter associated with a compact engine-and-transmission assembly will result in appreciable fuel savings and improved vehicle performance.
In view of this background, the present invention provides the advantageous features needed to substantially improve the efficiency and effectiveness of most land vehicles, motorized or not. For the simplicity, compactness and light-weight of its embodiments and constructions thereof also make it very attractive for other popular transportation vehicles, e.g. motorcycles.